The need for automation
and robotics grows stronger every day as labor costs rise and
competition from low-wage overseas locations intensifies. At the
same time, today’s product lifecycles are becoming shorter and the
demand for customization and subsequent part complexity grows
greater. Many products (not to mention their components) are
becoming smaller and tolerances tighter. Flexible, controlled
automation often is the only way to guarantee production efficiency
and high quality.

As a result of the advancements of automation in general
and robotics in particular, the assembly process is faster, more
efficient and more precise than ever before. Fortunately, as each
new generation of robot technology is introduced, speed and
performance improves and costs decrease. Automation and robotics
therefore become more affordable and valuable to the manufacturer.
Conventional wisdom of the past steered some assemblers to the
Cartesian coordinate robot, which consists of an orthogonal axis
structure.

“Two- and three-axis,
non-servo Cartesian devices have a lot of components like cylinders,
solenoids, tubing, and switches,” explains James C. Cooper,
Distribution Network Account Manager for FANUC Robotics America Inc.
“This complexity leads to several points of potential failure, but
that can all be replaced by one of our robots, at a significantly
higher mean time between failure, which is now 78,000 hours for our
robots.”

SCARA
Explained

The current most popular
robotics solution for assembly is the four-axis SCARA robot arm,
which can
move to any X-Y-Z coordinate within its work envelope. There is a
fourth axis of motion, which is the wrist rotation. The X, Y, and
roll movements are obtained with three parallel-axis rotary joints.
The vertical Z motion is usually an independent linear axis at the
wrist or in the base. SCARA robots are typically used in 2D assembly
operations where the final move to insert the part is a single
vertical motion. Component insertion into printed circuit boards is
an example. SCARAs are very common in pick-and-place, assembly and
packaging applications.

“You could do a specific
pick and place with a pneumatic mechanism, but if you get into an
application where you needed to possibly shift the part or rotate
the part, then you’re adding two or more mechanisms together,” says
Mike English, president of the Warwick, RI-based integrator
Interplex Automation. “With how robot prices have come down so much
over the years, I could design and build a pick-and-place unit and
by the time I put all the slides together and make or buy adaptor
plates, put sensors on the mechanism, assemble it, wire it, plumb
it, and add up my raw material cost and my labor cost, it’s about
the same as what a robot’s going to cost. With a robot, you just
bolt it to a table, program it and it’s ready to
go.”

The advantages of a
vertically articulated robot compared to a SCARA are its flexibility
and dexterity.

“Sometimes work pieces
come into the robot cell at an angle and with SCARAs something has
to be done to make the part flat.That’s additional cost and
additional hardware,” Cooper explains. “With the dexterity of the
vertically articulated robot, you can use the robot to pick up and
re-orient the part.”

Five- and six-axis
articulating robots also are more adaptable to variations or changes
during a project, and offer more flexibility during and after a
program.

“The robot is
programmable where the pick-and-place unit isn’t,” English says.
“There are always changes in design and
process.”

English describes a
robot he first installed for assembly, after which it was asked to
help perform an in-process inspection. “The robot allows me to stop
along the way, vision inspect the part and place it either in the
reject bin or where it needs to go next in the process,” he says.
“That’s an easy change. I don’t need to build a whole lot of other
stuff. The robot is the material management
unit.”

Mark Senti, vice
president of Advanced Magnet Lab, Inc., an integrator based in
Melbourne,
FL, cites an example
where an odd-shaped circuit board is inserted into a tight-fitting
key fob. Both components were on the far edge of the specification
and to insert the circuit board, a six-axis FANUC robot was
programmed to first tilt and then roll it into
place.

“A four-axis solution
would make it almost impossible to insert that vertically,” Senti
says. “A six axis robot allows you to manipulate the part very
gently and very accurately. With hard automation, you’re stuck if a
change is made after installation. Robotics allows you to easily and
quickly adapt to these changes.”

Despite the advancements
in robotics, integrators still specify Cartesian and SCARA systems
because of their history of and reputation for high speed, high
precision, standard control platforms, and – until recently – lower
cost compared to five- or six-axis articulating
robots.

Cost Structure
Changing

In the past, the greater
flexibility and dexterity of articulating robots has been offset by
slightly slower speeds and higher costs. Because of that, and their
years of experience with Cartesians and SCARAs, many integrators and
manufacturers are more comfortable with these standard forms of
automation.

As articulating robotics
technology advances, however, many of the advantages associated with
Cartesian and SCARA robots are dwindling. Vertically articulated
robots are becoming faster, their control platforms smaller, and as
the technology matures, becoming less
expensive.

Vertical articulating
robots generally increase quality, reliability and performance while
greatly reducing risk. Engineering costs are a fraction of
traditional systems as a robot is a significant part of an assembly
system that is fully designed and proven, with fewer electrical and
mechanical components. Along with engineering, the cost to assemble,
setup, test, tear down and install are much greater when using
traditional pick and place devices.

Robots also are easier
to integrate requiring less time to debug and fine tune. They are
easier to maintain, just grease the joints every six months and
change the battery once a year. They are more reliable than
traditional systems and typically eliminate the total number of
components in a system by performing multiple
tasks.

Senti, of Advanced
Magnet Lab, is a big believer in robots and says he studies four key
factors when selecting a supplier. The company must have a large
selection of robots, a common platform, have application software
available to ease integration, and offer integrated sensors and
vision systems.

“When selecting a
particular robot for a project, my first choice is always a six-axis
robot, which provides greater flexibility, capability and inherently
reduces the risk in the project,” Senti explains. “For small parts
assembly, there’s the perception that SCARA and Cartesian robots are
better suited for the application. Today’s articulated robots are
equal to the task in terms of speed, precision and
cost.”

The LR Mate 200iC
from FANUC Robotics is a prime example of what Senti is referring
to, and it meets his criteria. It is a servo-driven mini-robot
offering best-in-class performance in a light, efficient, accurate
and nimble package. Its tabletop size, slimmer arm profile, lighter
weight, high dexterity, faster sustained speed and superior
positioning accuracies make it a viable alternative for countless
industrial and commercial applications, including assembly. It also
continues a trend toward offering more features for less cost than
the model it replaces.

Numerous
Benefits

“In
the last six or seven years there have been so many advancements in
robot technology,” says Mark Handelsman, manager of Industry
Marketing at FANUC Robotics. “Motors are smaller and more powerful.
Processor speed has increased significantly
since the last LR Mate was introduced. There’s a lot we can do today
that we couldn’t do a few years ago.”

Handelsman adds that
repeatability has increased two-fold and speed increased 50 percent
between the old and the new LR Mate.

With the increase in
speed and the lower cost, the LR Mate 200iC gives more
manufacturers and assemblers an opportunity to take advantage of the
benefits of articulating robots while sacrificing
nothing.

“We made a very focused
effort to put this product in the lower cost-more value part of the
assembly market,” says FANUC Robotic’s Cooper.

FANUC Robotics says its
new LR Mate 200iC will make previous users of Cartesian and
SCARA automation think seriously about moving to five- and six-axis
articulated robots.

One is the
R-30iA
Mate controller, which uses advanced
technology packaged in a proven,
reliable and efficient
controller design. FANUC Robotics’ plug-in design
provides flexibility for application specific
configurations and a common look and feel for a wide
range of users of the system. This integrated
peripheral machine control (PMC) provides ladder-logic
control for many peripheral
devices.

Vision and
Force

The iRVision
integrated robot vision system is ready-to-use and requires no
additional hardware except for a camera or sensor and cable. It
provides 2D or 3D robot guidance and/or an error-free proofing tool
to accomplish part location, presence detection and other operations
that normally require special sensors or custom
fixturing.

Integrated force sensors
provide 3D assembly using standard sensor setup schedules and
processes specific force control instructions that make the
intelligent robots easy to program and operate via the FANUC
iPendant.

They provide force and
motion control, for example, to insert a clutch unit into an
automatic transmission unit of an automobile. The clutch insertion
force schedule includes direction, contact force, approach velocity,
push force, rotation limits, search frequency and search amplitude
to perform the operation. Once the force schedule is set, a simple
force control instruction is added to the robot program to perform
the insert operation the exact same way every time. Other functions
include variable spline matching, contouring, a uniform pushing
force, and built-in diagnostics if sensor data is out of
range.

In addition to the
integrated vision, controller and force sensors, the LR Mate
200iC features six degrees of freedom, 0.02 mm (0.00079
inches) repeatability at full payload and full speed within the
entire robot work envelope. It has up to 5 kg (11 pounds) payload at
the wrist along with best in-class wrist movements and inertias for
real-world workpieces.

Lighter and more compact
than its predecessor, the LR Mate also has a slimmer arm to allow
operation in narrow spaces, giving it its ample horizontal stroke of
458 mm. Its tabletop size, slim wrist and small footprint permit
operation in tight work spaces, yet it can flip over backward for a
larger work envelope.

Performance
Leap

The new robot’s high
joint speeds maximize throughput and its high-precision Z motion was
once thought possible only with a SCARA. It is 50 percent faster
than the previous LR Mate and is able to do eight standard 1”-12”-1”
test cycles in .49 seconds. Its high rigidity and the most
advanced servo technology enable smooth motion without vibration in
high-speed operation.

“We had a very
significant leap in performance with this most recent series, that’s
what’s opening the market,” Cooper says. “Almost a 50 percent
improvement in speed. That’s huge.”

The LR Mate
200iC’s reliability stems from its being the latest
generation of a proven design. It has sealed bearings and brushless
AC motors, an enclosed mechanical design that eliminates cables and
hose snagging and has grease fittings on all lubrication points for
quick and easy preventive maintenance. Further enhancing its
reliability is its collision detection and singularity avoidance
software. Singularity is the phenomenon that occurs when an
articulating robot’s joints line up.

With the same footprint
and wrist bolt pattern as the previous-generation LR Mate, upgrade
to the LR Mate 200iC is seamless.

Another reason to make
the switch to articulating robots is their reusability. For example,
the LR Mate can be reprogrammed to do new tasks and still perform
the original task.The
robot can jump to the right part program based on an input
device.Hard automation
can do one task, either the original or the new, not both.

“Flexibility is big for
the customer,” English explains. “A product line might last three or
four years. Then they want to retool things. They could take that
robot and use it somewhere else or for a new task -- that’s a key
advantage over hard automation.”

“If a customer has the
foresight to see that they have other potential programs in the
future, they really need to take the flexibility and re-use aspect
of robots into consideration,” English
says.